1. Field of the Invention
This invention relates to instruments for performing internal surgical procedures and, more particularly, to a guide for facilitating the controlled direction of a surgical instrument into a body cavity.
2. Background Art
Recently it has become possible to access and cannulate the fallopian tubes through the cervix, uterus and utero-tubal junction using a vaginal approach. This is becoming increasingly popular because the procedures are performed in outpatient settings without surgical incisions. Some of the cannulation procedures utilizing this approach include: (1) opening blocked tubes with a small catheter carrying a balloon or with a guide wire or a combination thereof (balloon tuboplasty); (2) injecting dye selectively into the fallopian tubes for x-ray visualization (selective salpingography); (3) injection of semen into the tube (intratubal insemination); (4) deposition of embryos or gamete mixtures into the tube (intratubal embryo transfer); and (5) direct visualization of the tubal lumen with small fibrooptic flexible telescopes.
Tubal cannulation through the distal fimbrial end continues to be a popular procedure performed at laparoscopy. Existing devices utilize the concept of catheters with preformed curves to access the tubal ostia. These catheters may be constructed from bent, relatively heavy gauge metal tubing. Alternatively, the preformed curve may be maintained in flexible tubing with metallic guide wire and/or memory of the tubing, made from plastic, or the like.
To accommodate anatomic variations in the uterus, devices are made with different preformed curves. Current devices suffer from the following common limitations. (1) It is often difficult to traverse the cervical canal and gain entrance into the uterine cavity using devices with a stiffened preformed curve. The curved device may not easily pass through the straight cervix. (2) Once inside the uterine cavity, it is not easy to position the device to one side or another because the uterine cavity is shaped like a flat envelope that does not possess a significant depth dimension. The curved device can get distorted and cause the patient pain in the process of turning because there is no room for the curved portion to turn in the flat cavity. Further, it is difficult to maintain the line of the bent free end in the device in a desired orientation. Rotation of the device even a small amount about its length may completely misalign the working free end of the device. (3) Although it is useful to accommodate the individual angle variations of the uterotubal junction with devices having different curves, that entails using more than one device to accomplish a good fit. The introduction of several devices into the uterus makes the procedure less economical, more painful, and subjects the patient to increased risk of infection and bleeding. (4) The absence of uterine measurements at the time of the procedure may cause uterine injury if the device is inserted deeper than indicated by the length of the uterus or result in malposition of the catheter if the device is withdrawn excessively. (5) The absence of a stable orientation and position of the device relative to the uterus may cause the device to become misoriented or displaced during manual manipulation of a small inner catheter directed therethrough. It is common to remove a wire, or the like, that guides the device into place after the device is fully inserted. This may result in deformation and misalignment of the device.
It is also known to both seal the cervix opening and fix the device relative to the cervix by using inflatable membranes. The inflation of a membrane in the uterus can cause pain and cramping. Further the membrane can cause uterine spasms and distortion of the uterus that may inhibit the effective performance of various procedures.